Optimum muscarinic potency has heretofore been assumed to require the presence in the drug of ether oxygen of muscarine. This work has provided the synthetic scheme for several carbocyclic analogs of muscarine which lack the ether oxygen yet retain very appreciable muscarinic potency. One, (plus or minus)-trans-l-hydroxy-cis-2-methyl-4-trimethylammonio' methylcyclopentane iodide, was obtained via a stereospecific photochemical pathway and was shown to be a direct muscarinic agonist possessing a potency of .1 - .5 times that of muscarine. These results indicate a need to consider further the muscarinic drug-receptor theory.